Fixes #11924 - Substitute .scoped by .where(nil) to force return relation

On Rails 4 .scoped is deprecated. Calling .all on the model returns the
equivalent ActiveRecord relation object on Rails 4, but on Rails 3 it
returns an Array right away.

A proper replacement we can use is where(nil) - it's ugly but it returns...

fixes #9981 - making sure lookup_keys with errors get displayed if they're broken

Fixes #12089 - fix using unwrapped parameters in config templates API controller

Fixes #11921 - load dynamic features during runtime

Fixes #11237 - documenting hostgroup association to compute profile

Fixes #10988 - Remove 1.11 deprecations

Refs #10409 - Rails 4 compatible changes with Rails 3

This includes some changes that can be applied to Rails 3 without
any issue and don't follow any particular pattern/deprecation, In
general these are minor things we have to change. Other PRs with
retrocompatible changes that aim to fix particular deprecations...

fixes #11996 - use preload to avoid multiple fact/host table joins

When retrieving fact_values as a non-admin user, the my_facts scope
performs a join to the hosts table. The .includes(:host) also performs
a join via eager loading, and when both are combined with a scoped...

Fixes #11767 - avoid cleaning of interface attributes

Fixes #11764 - Taxonomy parameters can be accessed through API